Influence of the flesh quality and body size on the auction price of parrotfishes (Scaridae) at tropical island, southern Japan: Implications for fisheries management

• Published in: Regional studies in marine science 2019-01, Vol.25, p.100489, Article 100489
• Main Authors: Shimose, Tamaki, Kanaiwa, Minoru, Nanami, Atsushi
• Format: Article
• Language: English
• Subjects: Auction; Bid price; Chlorurus microrhinos; GLM; Isolated island
• ISSN: 2352-4855; 2352-4855
• DOI: 10.1016/j.rsma.2018.100489

Bid price of fish at auction is dependent on the situation of the date (season and supply) and quality of the fish (species, size, and freshness). In this study, how bid prices for parrotfishes (Scaridae spp.) determined at auction were investigated in a tropical island, southern Japan (Yaeyama fish market, Okinawa) between April 2011 and March 2015. Six factors, i.e. month, supply, size of fish, fishing gear type, bruising on the body, and endo-parasitic infection were chosen as variables, and their effects on bid prices were investigated using a generalized linear model with a log-normal error distribution in six selected species (Chlorurus microrhinos, Hipposcarus longiceps, Scarus ghobban, S. rivulatus, S. rubroviolaceus, Bolbometopon muricatum). All variables significantly affected the prices. The effects of supply were thought to remain for up to seven days from the AIC (Akaike’s Information Criterion) comparison, and the supply affected prices more than month did. For all species, the prices increased with fish size for smaller size ranges, but inversely decreased for larger size ranges. Prices of medium sized species took the highest values at 1.0–2.0 kg in size. Scarid fishes were mainly caught by spearfishing at night, but spear bruising on the body, parasitic infection, and being caught by gillnet significantly reduced prices (ca. minus 200–300 yen/kg for each case). Results obtained here are useful to increase the catch of higher quality fish by regulation (size, season, site etc.), to help reduce risk of price collapse triggered by large catch (oversupply), and to enable discussion of appropriate fisheries management practices.